Processing of colour photographic materials in the presence of a competing coupler

ABSTRACT

THIS APPLICATION DESCRIBES A PROCESS OF COLOUR-DEVELOPMENT OF COLOUR PHOTOGRAPHIC MATERIAL WHEREIN AT LEAST ONE SILVER HALIDE EMULSION LAYER CONTAINING A DEVELOPABLE SILVER SALT IS COLOUR DEVELOPED TO YIELD A DYE IMAGE, THE DEVELOPED SILVER AND THE RESIDUAL SILVER HALIDE BEING REMOVED, THERE IS PROVIDED THE STEP OF DEVELOPING THE PHOTOGRAPHIC MATERIAL WITH A COLOUR DEVELOPING SOLUTION WHICH CONTAINS ALKALI METAL SULPHITE IN THE PRESENCE OF AN IMAGEFORMING COLOUR COUPLER AND A COMPOUND OF THE FOLLOWING GENERAL FORMULA:   2-(R1-O-),4-R2-PHENOL   WHERE R1 IS AN ALKYL GROUP CONTAINING UP TO 6 CARBON ATOMS AND R2 IS HYDROGEN OR AN EASILY DISPLACEABLE SUBSTITUENT GROUP.

United States Patent 3,560,212 PROCESSING OF COLOUR PHOTOGRAPHIC MATERIALS IN THE PRESENCE OF A COM- PETIN-G COUPLER Eric MacDonald, Holcombe Brook, England, Billie Nam,

Lexington, Mass., and David Price, 'Chelmsford, England, assignors to Ilford Limited, Ilford, England No Drawing. Filed Oct. 23, 1967, Ser. No. 677,059 Claims priority, application Great Britain, Oct. 28, 1966, 48,492/66 Int. Cl. G03c 7/02 US. C]. 9655 7 Claims ABSTRACT OF THE DISCLOSURE This application describes a process of colour-development of colour photographic material wherein at least one silver halide emulsion layer containing a developable silver salt is colour developed to yield a dye image, the developed silver and the residual silver halide being removed, there is provided the step of developing the photographic material with a, colour developing solution which contains alkali metal sulphite in the presence of an imageforming colour coupler and a compound of the following general formula:

where R is an alkyl group containing up to 6 carbon atoms and R is hydrogen or an easily displaceable substituent group.

This invention relates to a colour development process and especially to the processing of photographic material which contains colour couplers.

One of the difliculties associated with the processing of colour photographic material which contains substantive colour couplers has been to balance correctly the amount of silver halide compared to colour coupler in each layer of normal tri-pack material. If theoretically the correct amount of colour coupler is present to combine with all the oxidised colour developer which would be formed it all the sliver halide were reduced, a resultant dye image would be formed of too high a contrast as a dye image has pro rata a much higher covering power than a silver image. If however the amount of silver is lowered to such an amount that an acceptable resultant dye image could be expected, a very grainy image often results with a resultant lessening in the sharpness and definition of the image. One method of overcoming this difiiculty has been to employ, with the substantive colour coupler, a so called competing colour coupler. When photographic material containing in each emulsion layer a substantive colour coupler and a relatively large amount of silver halide is exposed and developed in the presence of such a competing colour coupler the oxidised colour developing agent combines with the substantive colour coupler in each emulsion layer and with the competing colour coupler which may be in each emulsion layer or in the colour developing solution. The competing colour coupler forms 3,560,212 Patented Feb. 2, 1971 a non-substantive dye which is water soluble and some therefore is removed from the material in the developing solution, the remainder being removed by a water-washing step immediately after the development step. This build-up of colour in the colour developing solution tends to cause difficulties in the continuous analysis of the colour developing solution (necessary for control purposes), especially when absorption analytical methods are used.

It is an object of the present invention to provide a colour development process wherein part of the oxidised colour developer is removed from the system without forming an image dye, and wherein the tendency to colour the colour developing solution is reduced or minimised.

According to the present invention in a process of colour development of colour photographic material wherein at least one silver halide emulsion layer containing a developable silver salt is colour developed to yield a dye image, the developed silver and the residual silver halide being removed, there is provided the step of developing the photographic material with a colour developing solution which contains alkali metal sulphite in the presence of an image-forming colour coupler and a compound of the following general formula:

where R is an alkyl group containing up to 6 carbon atoms and R is hydrogen or an easily displaceable substituent group such as aminoalkyl, halogen or SO H.

The compound of the above defined formula is able to couple with oxidised colour developing agent to form a dye but this dye is at once decolourised by the presence of the alkali metal sulphite in the colour developing solution.

The preferred compounds of the above defined formula are 2-methoxy phenol, known as guiacol, and 2-methoxy- 4-aminoethyl phenol which is known as vanillylamine. This later compound is preferably used as vanillylamine hydrochloride but it is converted in the presence of the alkaline colour developing solution to yield free vanillylamine.

In a preferred embodiment of the invention in order to ensure that all the dye formed, when a compound of the above formula couples with oxidised colour developing, is decolourised, there is included in the process of colour development the additional step of treating the material subsequent to colour development with an acid-containing solution such as an acid hardening stop bath.

The process of the present invention is particularly of use in the processing of a multilayer colour material of the type in which there are three gelatino silver halide emulsion layers, selectively sensitive to blue, green and red regions of the spectrum, each layer containing a colour coupler substantive thereto, which yields on colour development a dye image complementary in colour to the colour sensitivity of the layer containing it. The colour material may be of the type which yields a direct colour image on development or may be of the type which is used to produce reversal colour images. It is applicable in the reversal processing of colour photographic material wherein the image-forming colour couplers are not present initially but are present in each colour developing solution.

It is preferred that the compounds of the above formula are present in the colour developing solution or solutions but they may be present initially in the photographic material and in this case preferably in each silver halide containing layer.

When the compounds of the above formula are present in the colour developing solution they are preferably present at a concentration of 0.5 to g./litre. In the case of colour coupler substantive material the exact concentration depends on the desired effect and on the silver halide/ colour coupler coating weight.

The examples set out later herein relate to photographic material of the reversal type. The usual processing sequence for exposed material of this type comprises the following steps which are well known in the art:

Black and white development. Hardening bath.

Washing bath. Re-exposure.

Colour development.

Wash and/ or acid stop bath. Bleach.

Washing bath.

Fixing bath.

() Washing bath.

( l l Conditioning treatment.

The only factor which is likely to vary greatly when processing different materials is the composition of the colour development bath. In Examples 1 and 2 which relate to a reversal material containing substantive colour couplers a colour development bath of the following composition was used:

Trisodium phosphate 80 Hydroxylamine sulphate 2.4

Anhydrous sodium sulphite 4.0-

Potassium bromide 1.0 N-ethyl-N-hydroxyethyl p-phenylene diamine sulphate 5.7

Water to 1 litre.

EXAMPLE 1 Maximum density R G B Standard colour developer 3. 31 2. 83 2. 81 Standard colour developer, plus 1.6 g./1. guaiacol 2. 19 2. 1.86

Examination of the dye images showed improved graininess on the addition of guaiacol.

EXAMPLE 2 A multilayer element was processed as described in Example 1 except that 2.0 g./l. of vanillylamine hydrochloride (2-methoxy-4-aminoethyl phenol hydrochloride) was added. The following changes in maximum colour density was observed with improved graininess.

Maximum EXAMPLE 3 A reversal material not containing substantive colour couplers may be processed according to the steps hereinbefore set forth in col. 3 where the colour development of step (5) is carried out with the addition of a colour coupler to the colour developing solution.

Accordingly two green sensitive silver halide emulsion coatings A and B were prepared containing respectively 16.6 and 22.2 mgm. of silver per dm. Strips of the material were sensitometrically exposed, black and white developed, hardened, washed and re-exposed. Colour development of a magenta image was produced in a colour developing bath of the following composition:

G. Trisodium phosphate Hydroxylamine sulphate 2.4 Anhydrous sodium sulphite 4.0 Potassium bromide 4.0 5-diethylamino-2-aminotoluene hydrochloride 2.0 1-phenyl-3-coumarilylamido-5-pyrazolone 2.0

Maximum Material Process density, G.

1 A N o completing coupler 1. 5 2 B do 2.3 3 B With competing coupler 1. 5

Examination of the dye images at equal densities showed improved graininess for process 3 in the presence of competing coupler compared to process 1 in the absence of competing coupler.

We claim as our invention:

1. In a process of colour development of colour photographic material wherein at least one siliver halide emulsion layer containing a developable silver salt is colour developed to yield a dye image, and the developed silver and the residual silver halide are removed, the improvement which comprises developing the photographic material with a colour developing solution which contains alkali metal sulphite in the presence of an image-forming colour complex and a compound of the following formula:

where R is an alkyl group containing up to 6 carbon atoms and R is hydrogen or an easily displaceable sub stituent group.

2. A process according to claim 1 which comprises the additional step of treating the material subsequent to colour development with an acid-containing solution.

3. A process according to claim 1 wherein the compound of the formula defined therein is present in the colour developing solution.

4. A process according to claim 3 wherein the compound of the formula defined in claim 1 is present in the colour developing solution at a concentration of 0.5 to 5 g./1itre.

5. A process according to claim 1 wherein the easily displaceable substituent group is selected from aminoalkyl, halogen or SO H.

6. A process according to claim 1 wherein the compound of the formula defined therein is Z-methoxy phenol.

7. A process according to claim 1 wherein the compound of the formula defined therein is 2-1nethoxy-4- aminoethyl phenol.

References Cited UNITED STATES PATENTS 2,319,078 5/1943 MCNally et a1 9666X 2,689,793 9/1954 Weller et a1. 9655 3,108,001 10/1963 Green 9629 10 NORMAN G. TORCHIN, Primary Examiner A. T. SURO PICO, Assistant Examiner US. Cl. X.R. 9622 

